Assessing Multi-Species Cover Crop Responses to Variable Soil Moisture and Soil Types

Project Overview

Project Type: Graduate Student
Funds awarded in 2016: $11,928.00
Projected End Date: 05/31/2018
Grant Recipient: North Dakota State University
Region: North Central
State: North Dakota
Graduate Student:
Faculty Advisor:
Dr. Greta Gramig
North Dakota State University


  • Agronomic: grass (misc. annual), millet, oats, sunflower, vetches, cowpea, foxtail millet
  • Vegetables: greens (leafy)


  • Crop Production: conservation tillage
  • Natural Resources/Environment: soil stabilization
  • Pest Management: mulches - killed, weed ecology
  • Production Systems: organic agriculture
  • Soil Management: green manures, organic matter, soil analysis

    Proposal abstract:

    The proposed project, entitled ‘Assessing multi-species cover crop responses to variable soil moisture and soil types,’ will compare monoculture and mixture cover crop performance under variable soil moisture regimes. In recent years, farmers have been encouraged to plant complex multi-species cover crop mixtures instead of cover crop monocultures. Some researchers and practitioners have suggested that complex cover crop mixtures are more productive or efficient than single species cover crops. In the northern Great Plains region, farmers often contend with limited precipitation. Therefore, the water use efficiency of cover crops is important, because cover crops use water that might be needed to grow a main crop. Furthermore, with climate change, drought periods in these areas may lengthen or intensify, leading to a greater need to conserve soil water resources. Limited research has been conducted to understand how complex cover crop mixtures perform in relation to monocultures under different soil moisture levels. Furthermore, little work has been done to quantify above-ground and root productivity of cover crops in mixtures or in monocultures under variable moisture conditions. For this project, three monoculture cover crops (foxtail millet, cowpea, and sunflower) will be compared to a three-species mixture (foxtail millet, cowpea, sunflower) and to a six-species mixture (foxtail millet, cowpea, sunflower, oat, hairy vetch, kale) under irrigated and dryland conditions at two locations in ND. Continuous soil moisture content will be recorded at 20 cm depth and spot measurements of near-surface soil moisture will be collected throughout the growing season. Soil cores will be collected at peak biomass at three depths to determine root density per unit soil volume and root biomass. Stomatal conductance for each cover crop species will be measured via a porometer to gauge water stress. Peak season above-ground biomass will be assessed for each cover crop treatment, separated by species. For each cover crop treatment, a water budget analysis will be conducted to determine water-use efficiency. At each stage of the project, progress will be evaluated using milestone dates to achieve specific project components. A better understanding of the benefits of multispecies cover cropping in relation to variable soil moisture will be the primary outcome of the project. The results of this study will be relevant to farmers who are being encouraged to plant multi-species cover crops, but who are concerned because the benefits of planting these types of cover crops under variable moisture conditions have not been thoroughly documented.

    Project objectives from proposal:

    This project will assess multi-species cover crop responses to variable soil moisture and soil types,’ will compare monoculture and mixture cover crop performance under variable soil moisture regimes. The results will be relevant to farmers because many farmers are being encouraged to plant multispecies cover crops, but the benefits of planting these types of cover crops under altered precipitation have not been thoroughly documented. The results of this study will benefit both organic and conventional farmers who are interested in using multi-species cover crops but are concerned about water use efficiency and productivity. Although we will evaluate a subset of possible cover crop species and multi-species combinations, we plan to use the results as preliminary data to apply for a larger grant to extend the results to many more species. Through outreach efforts at two field days, 50 farmers will learn about how multi-species cover crops may perform under different levels of soil moisture typically encountered in the northern Great Plains. This information will help farmers who are hesitant about using cover crops decide if and how multi-species cover crops might be incorporated into their production systems. We will conduct surveys among field day participants to document how knowledge about multi-species cover crop mixes and water use efficiency changed as a result of the proposed project. We will also ask field day participants to complete an online survey approximately three months after the initial field day to assess how our results impacted the actions (i.e., increase or decrease planting of multi-species cover crops) of participating farmers. We expect that approximately five farmers will decide to change their cover cropping strategies as a result of being exposed to our research results. The proposed project will result in approximately 4000 scientists/researchers and 3000 farmers/practitioners/dealers learning about multi-species cover crop water use efficiency at two conferences (American Society of Agronomy Annual Conference and MOSES Organic Farming Conference).  

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.